This invention generally relates to catheters, and particularly intravascular catheters for use in percutaneous transluminal coronary angioplasty (PTCA) or for the delivery of stents.
In a typical PTCA procedure, a dilatation balloon catheter is advanced over a guidewire to a desired location within the patient's coronary anatomy where the balloon of the dilatation catheter is positioned within the stenosis to be dilated. The balloon is then inflated with radiopaque liquid at relatively high pressures (generally 4-16 atmospheres) to dilate the stenosed region of the diseased artery. One or more inflations may be needed to effectively dilate the stenosis. Additionally, a stent may be implanted within the artery, typically by delivery to a desired location within the artery in a contracted condition on a balloon of a catheter which is similar in many respects to a balloon angioplasty catheter and expansion to a larger diameter by inflation of the balloon.
An essential step in effectively performing a PTCA procedure is properly positioning the balloon catheter at a desired location within the coronary artery. To properly position the balloon at the stenosed region, the catheter must have good pushability and flexibility, to be readily advanceable within the tortuous anatomy of the patient's vasculature. U.S. Pat. No. 5,300,085 shows a balloon dilatation catheter having a single lumen proximal section, a coaxial lumen distal section formed by an inner tubular member coaxially disposed within an outer tubular member, and a guidewire port at a transition region spaced a substantial distance from the proximal end of the catheter and about 10-15 centimeters from the distal extremity of the catheter. The transition region is formed by bonding the proximal end of the outer tubular member of the coaxial lumen distal section around a short section of the distal end of the proximal section and the proximal end of the inner tubular member of the coaxial lumen distal section. It has been found that the catheter shown in the U.S. Pat. No. 5,300,085 patent may, on occasion, have suboptimal pushability.
What has been needed is a catheter which is highly trackable within the patient's anatomy, with improved flexibility and pushability. The catheter of the present invention provides these and other advantages.